Air conditioner system with defrost door modulation as a function of ambient temperature

ABSTRACT

The operation mode of an air conditioner system is automatically controlled between VENT mode, BI-LEVEL mode, HEAT mode and so forth according to environmental conditions. The air conditioner system includes a control unit for operation mode selection. In HEAT mode, the control unit adjusts ratio of the conditioning air discharged from a defroster nozzle to that from a foot nozzle according to environmental conditions or on the basis of a required discharge air temperature necessary to obtain a desired air temperature in the vehicular cabin. The air conditioner system also includes a sensor for monitoring a preselected air conditioner control parameter for producing a sensor signal. The control unit calculates the required discharge air temperature on the basis of the monitored parameter.

This application is a continuation of application Ser. No. 07/190,393,filed May 5, 1988, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an air conditioner system forautomotive vehicles. More specifically, the invention relates to an airconditioner system which can adjust temperatures of conditioned airdischarged from a defroster nozzle and a foot vent nozzle. Furtherspecifically, the invention relates to an air conditioner system whichcan discharge lower temperature conditioned air from the defrosternozzle and higher temperature conditioned air from the foot vent nozzleso as to supply warm air at the occupant in a vehicular cabin's feet andstill prevent the window glasses from being clouded up.

2. Description of the Prior Art

Various automatic air conditioner systems, which automatically adjustdischarge air temperature to achieve comfortable conditions in avehicular cabin, have been proposed. One such automatic air conditionersystem was disclosed in the Japanese Utility Model First Publication(Jikkai) Showa 58-79414.

Such conventional automatic air conditioner systems discharge warmconditioning air from a foot nozzle to warm the vehicular occupant'sfeet and discharge cooler conditioning air from a defroster nozzle toremove condensation from windshield glass, when the system operates inHEAT mode. In such systems, the air flow rate is constant so as toeffectively de-frost the windshield, or to prevent the windshield frombecoming clouded up, at an estimated low ambient te e, for example, at-10° to -20° C.

However, such systems discharge more conditioned air than that actuallynecessary to de-fog the windshield glass when the ambient temperature isnot so low, fcr example, at 0° to 30 10° C., which can cause theoccupant to feel uncomfortably warm.

SUMMARY OF THE INVENTION

It is therefore a principal object of the present invention to providean air conditioner system for an automotive vehicle, which can changethe rate of air flow from a defroster nozzle to prevent the occupantfrom feeling to warm and to increase comfort of the vehicular cabin.

In order to accomplish the aforementioned and other specific objects, anair conditioner system for an automotive vehicle includes flow rateadjusting means for controlling the proportion of air flow dischargedfrom a defroster nozzle to that from a foot nozzle.

According to one aspect of the present invention, the air conditionersystem for automotive vehicles comprises:

conditioning air passage unit defining a conditioning air path andincluding first and second air outlets which open to a vehicular cabinfor discharging a conditioning air into the vehicular cabin;

conditioning air generating unit disposed within the conditioning airpassage unit, the conditioning air generating unit including a coolingair unit for cooling the air flowing through the conditioning air pathand a heating unit for heating the air flowing through the conditioningair path, the cooling and heating units being cooperative for generatingconditioning air of a desired temperature;

a first door associated with the first air outlet operable between aclosed position in which the first door fully closes the first airoutlet in a first operation mode of the air conditioner system and anopen position in which the first door fully open the first air outlet ina second operation mode of the air conditioner system;

a second door associated with the second air outlet operable between aclose position in which the second door fully closes the second airoutlet in the second operation mode and an open position in which thesecond door fully opens the second air outlet in the first operationmode;

actuator unit for driving the first and second doors for varying theopening angles of the first and second doors between the closedpositions and open positions; and

control unit for selecting one of the first and second operation modesand a third operation mode, in which conditioning air is discharged fromthe first and second outlets, associated with the actuator unit, foradjusting the ratio of the conditioning air discharged from the firstoutlet to that from the second outlet in the third operation mode.

The air conditioner system may also includes a sensor unit formonitoring a preselected air conditioner control parameter for producinga sensor signal representative of a monitored parameter. The controlunit may select one of the operation modes for adjusting theaforementioned ratio on the basis of the sensor signal of the monitoredparameter. The sensor means may include an insolation sensor formonitoring the magnitude of insolation for producing a sensor signalindicative of the magnitude of insolation, an ambient temperature sensorfor monitoring the ambient air temperature for producing a sensor signalindicative of the ambient temperature, and an inlet temperature sensor,disposed between the cooling unit and the heating unit, for monitoringthe temperature of the air passing through the cooling unit forproducing a sensor signal indicative of temperature of the air. Thecontrol unit may include a microcomputer having a control program forprocessing the sensor signals. The control means may be manuallyoperable by means of a manually operable switch assembly. The controlunit may also select one of the operation modes for adjusting theaforementioned ratio on the basis of a required discharge airtemperature necessary to obtain a desired air temperature in thevehicular cabin. The control unit may further calculate a requireddischarge air temperature necessary to obtain a desired air temperaturein the vehicular cabin, on the basis of the sensor signals, and selectone of the operation modes for adjusting the aforementioned ratio on thebasis of the required discharge air temperature. The control means mayalso calculate the required discharge air temperature necessary toobtain a desired air temperature in the vehicular cabin, on the basis ofthe sensor signals, and selects one of the operation modes for adjustingthe aforementioned ratio on the basis of the required discharge airtemperature.

According to another aspect of the invention, the air conditioner systemcomprises:

conditioning air passage unit defining a conditioning air path andincluding first and second air outlets which open to a vehicular cabinfor discharging a conditioning air into the vehicular cabin;

conditioning air generating unit disposed within the conditioning airpassage unit, the conditioning air generating unit including a coolingair unit for cooling the air flowing through the conditioning air pathand a heating unit for heating the air flowing through the conditioningair path, the cooling and heating units being cooperative for generatingconditioning air of a desired temperature;

a first door associated with the first air outlet operable between aclosed position in which the first door fully closes the first airoutlet in a first operation mode of the air conditioner system and anopen position in which the first door fully opens the first air outletin a second operation mode of the air conditioner system, the first doorbeing positioned at an intermediate position between the open and closedpositions in a third operation mode of the air conditioner system andbeing positioned at the open position in a fourth operation mode of theair conditioner system;

a second door associated with the second air outlet operable between aclosed position in which the second door fully closes the second airoutlet in the second operation mode and an open position in which thesecond door fully opens the second air outlet in the first operationmode, the second door being positioned at the open position in the thirdand fourth operation modes;

actuator unit for driving the first and second doors for varying openingangles of the first and second doors between the closed positions andopen positions; and

control unit for selecting one of the operation modes, associated withthe actuator unit, for adjusting the ratio of the conditioning airdischarged from the first outlet to that from the second outlet.

The air conditioner system may also include a sensor unit for monitoringa preselected air conditioner control parameter for producing a signalrepresentative of a monitored parameter. The control unit may select oneof the operation modes for adjusting the aforementioned ratio on thebasis of the monitored parameter. The sensor unit may include aninsolation sensor for monitoring the magnitude of insolation forproducing a sensor signal indicative of the magnitude of insolation, anambient temperature sensor for monitoring the ambient air temperaturefor producing a sensor signal indicative of the ambient temperature, andan inlet temperature sensor, disposed between the cooling unit and theheating unit, for monitoring temperature of the air passing through thecooling unit for producing a sensor signal indicative of temperature ofthe air. The control unit may include a microcomputer having a controlprogram for processing the sensor signals for selecting one of theoperation modes. The control unit is also manually operable by unit of amanually operable switch assembly. The control unit may also select oneof the operation modes on the basis of a required discharge airtemperature necessary to obtain a desired air temperature in thevehicular cabin. The control unit may calculate a required discharge airtemperature necessary to obtain a desired air temperature in thevehicular cabin, on the basis of the sensor signals, and select one ofthe operation modes on the basis of the required discharge airtemperature. The control unit may also calculate a required dischargeair temperature necessary to obtain a desired air temperature in thevehicular cabin, on the basis of the sensor signals, and select one ofthe operation modes on the basis of the required discharge airtemperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the preferred embodiment of an airconditioner system according to the present invention;

FIG. 2 is a perspective view of the preferred embodiment of aconditioning air duct assembly according to the invention;

FIG. 3 is a sectional view of the conditioning air duct assembly takenalong the line III--III of FIG. 2; air duct assembly of FIG. 2;

FIG. 5 is an expanded side elevation of a rear air passage of theconditioning air duct assembly in FIG. 2;

FIG. 6 is a fragmentary sectional view of the rear air passage takenalong the line VI--VI;

FIG. 7 is a block diagram of a front control unit which controls the airconditioner system in FIG. 1;

FIG. 8 is a plan view of a front control panel on which manual switchesfor controlling the air conditioner system of FIG. 1 are installed;

FIG. 9 is a block diagram of a rear control unit which controls the airconditioner system in FIG. 1, and units connected to the rear controlunit;

FIG. 10 is a plan view of a rear control panel on which manual switchesfor controlling the air conditioner system of FIG. 1 for the back seatare installed;

FIG. 11 is a flow chart showing a process for controlling the airconditioner system of FIG. 1 by the front control unit of FIG. 7;

FIG. 12 is a flow chart of a control program for processing datasupplied by an ambient air temperature sensor in the process of FIG. 11;

FIG. 13 is a flow chart of a control program for processing datasupplied by an insolation sensor in the process of FIG. 11;

FIG. 14 is a flow chart of a control program for correcting the setcabin temperature in the process of FIG. 11;

FIG. 15 a flow chart of a control program for calculating opening angleof the air-mix door in the process of FIG. 11;

FIG. 16 is a flow chart of control a program for controlling acompressor of the air conditioner system of FIG. 1 in the process ofFIG. 11;

FIG. 17 is a flow chart of the first preferred embodiment of a controlprogram for controlling discharge nozzles of the air conditioner systemof FIG. 1 in the process of FIG. 11;

FIG. 18 is a flow chart of a control program for controlling inlets ofthe air conditioner system of FIG. 1 in the process of FIG. 11;

FIG. 19 is a flow chart of a control program for controlling the airflow rate of the air conditioner system of FIG. 1 in the process of FIG.11;

FIG. 20 a flow chart showing a process for controlling the airconditioner system of FIG. 1 by the rear control unit of FIG. 9;

FIG. 21 is a flow chart of a control program for controlling aseparating door of the air conditioner system of FIG. 1 in the processof FIG. 20;

FIG. 22 is a flow chart of a control program for controlling a rearair-mix door of the air conditioner system of FIG. 1 in the process FIG.20;

FIG. 23 is a graph of the relationship between the position of a manualswitch for the fine adjustment of the set temperature in the back seatand the set temperature TPTCRR set by the manual switch;

FIG. 24 is a flow chart of a control program for controlling a selectingdoor assembly of the air conditioner system of FIG. 1 in the process ofFIG. 20; and

FIG. 25 is a flow chart of the second preferred embodiment of a controlprogram for controlling discharge nozzles of the air conditioner systemof FIG. 1 in the process of FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, particularly to FIG. 1, the preferredembodiment of an air conditioner system for an automotive vehicleincludes a conditioning air duct assembly 10 which comprises a blowerhousing 12, a cooler unit housing 14 and an air mixing unit housing 16.

The blower housing 14 defines air inlets 18 and 20. The inlet 18 drawsair from the outside of the vehicular body. The air inlet 18 will bereferred to as "fresh air inlet". On the other hand, the air inlet 20draws air from the vehicular cabin. The air inlet 20 will be referred toas "recirculation air inlet". The fresh air inlet 18 and therecirculation air inlet 20 are selectively opened and closed by means ofan air intake door 22. The air intake door 22 is hinged on the wall ofthe blower housing 12 to be operated between a recirculation air modeposition pl and fresh air mode position P3. At the recirculation airmode position P1 of the air intake door 22, the fresh air inlet 18 isclosed and the recirculation air inlet 20 is fully opened. On the otherhand, at the fresh air mode position P3 thereof, the recirculation airinlet 20 is closed and the fresh air inlet 18 is fully opened.Therefore, when the air intake door 22 is disposed at the position P3,only the fresh air is introduced into the blower housing 12, and when itis disposed at the position P1, only the air from the vehicular cabin isintroduced thereto. Moreover, when the air intake door 22 is disposed ata position P2 between the positions P1 and P3, both of the fresh air andthe air from the vehicular cabin are introduced into the blower housing12. The air intake door 22 is driven by an actuator motor Ml.

The blower housing 12 also defines a space for receiving a blower 24.The blower 24 is disposed at a location beneath the fresh air inlet 18.The air introduced through the fresh air inlet 18 or the recirculationair inlet 20, is blown against an evaporator 26 by means of the blower24. Refrigerant in the evaporator 26 is supplied to a compressor 28. Apulley 30 is fixed to the rotary shaft of the compressor 28, and apulley 32 is fixed to the rotary shaft of an engine 34. Moreover, a belt36 is stretched over the pulleys 30 and 32, so that the compressor 28can be driven by the engine 34. As will be described hereafter, when amagnetic clutch is turned on in response to a control signal producedfrom a front control unit 38, the driving force of the engine 34 issupplied to the compressor 28 by means of the belt 36. The refrigerantsupplied to the compressor 28 is changed thereby into high-temperature,high-pressure gas, and thereafter is supplied to a condenser 40 to becondensed. The refrigerant liquified in the condenser 40 is stored in aliquid tank 42. The liquid tank 42 is in communication with theevaporator 44, which is housed in the cooler unit housing 14, via anexpansion valve 46. By adjusting opening angle of the expansion valve46, a difference between the pressures in the liquid tank 42 and theevaporator 44 can be produced. Therefore, the evaporator 44 absorbs theheat of the air flow from the blower 24 which is directed against theevaporator 44, when the liquid refrigerant in the liquid tank 42 isintroduced into the evaporator 44 to be vaporized. As a result, thetemperature of the air surrounding the evaporator 44, i.e. temperatureof the air flow directed from the blower 24 against the evaporator 44,is decreased.

The conditioning air duct assembly 10 branches behind the evaporator 44.The air flow cooled by the evaporator 44 is introduced into respectiveconditioning air passages 48 and 50 for supplying the air to the frontand rear vehicular occupants, which will be hereafter referred to as"front air passage" and "rear air passage". The air introduced into thefront and rear air passages 48 and 50 is blown against a heater core 52housed in the air mixing unit housing 16. The proportion of air flowpassing through the heater core 52 to that bypassing the latter isdetermined by front and rear air-mix doors 54 and 56 which are providedwithin the front and rear air passages 48 and 50, respectively. Coolingair from the engine 34 is supplied to the heater core 52, and thetemperature of the cooling water increases as the temperature of theengine 34 increases. The front air-mix door 54 is hinged on the wall ofthe heater core 52 to be operated between positions P4 and P5. When thefront air-mix door 54 is disposed at the position P4, the air cooled bythe evaporator 44 does not pass through the heater core 52, so thetemperature of the air passing through the front air passage 48 is notincreased. On the other hand, when the front air-mix door 54 is disposedat the position P5, the air cooled by the evaporator 44 passes throughthe heater core 52, so that the temperature thereof is increased.Therefore, in accordance with opening angle of the front air-mix door54, the amount of the air passing through the heater core 52 can bechanged for adjusting the temperature of the air passing through thefront air passage 48. The rear air-mix door 56 is also hinged on thewall of the heater core 52 to be operated between positions P6 and P7.When the rear air-mix door 56 is disposed at the position P6, the aircooled by the evaporator 44 does not pass through the heater core 52, sothat the temperature of the air passing through the rear air passage 50is not increased. On the other hand, when the rear air-mix door 56 isdisposed at the position P7, the air cooled by the evaporator 44 passesthrough the heater core 52, so that the temperature thereof isincreased. Therefore, in accordance with opening angle of the rearair-mix door, the amount of the air passing through the heater core 52can be changed for adjusting the temperature of the air passing throughthe rear air passage 50. The front and rear air-mix doors are driven bymeans of actuators M2 and M3, respectively.

The front air passage 48 defines a front defroster nozzle 58, a frontvent nozzle 60 and a front foot nozzle 62. The defroster, vent and footnozzles 58, 60 and 62 are selectively opened and closed by means of afront defroster door 64, a front vent door 66 and a front foot door 68,respectively. The front defroster door 64 is hinged on the wall of thefront air passage 48 to be operated between positions P8 and P10. Whenthe front defroster door 64 is at the position P10, the amount of theair discharged from the front defroster nozzle 58 is maximum. At theposition P8, no air is discharged from the front defroster nozzle 58.When the front defroster door 64 is disposed at a position P9 betweenthe positions P8 and P10, a small amount of air is discharged from thefront defroster nozzle 64. The front vent door 66 is also hinged on thewall of the front air passage 48 to be operated between positions P11and P12. When the front vent door 66 is at the position P11, no air isdischarged from the front vent nozzle 60. On the other hand, at theposition P12, air is discharged from the front vent nozzle 60. Inaddition, the front foot door 68 is hinged on the wall of the front airpassage 48 to be operated between positions P13 and P14. At the positionP13 of the front foot door 68, no air is discharged from the front footnozzle 62. On the other hand, at the position P14 thereof, the air isdischarged from the front foot nozzle 62. The front defroster door 64,the front vent door 66 and the front foot door 68 are driven by anactuator motor M6.

An air passage 70 is formed in the wall between the front and rear airpassages 48 and 50, so that the air passing through the heater core 52in the rear air passage 50 can be introduced into the front air passage48. The passage 70 is opened and closed by means of a separating door72. The separating door 72 is hinged on the wall between the front andrear air passages 48 and 50 to be operated between positions p15 andP16. When the separating door 72 is at the position P15, the passage 70is closed so as to allow the air flow to be discharged from the rear airoutlets. At the position P16 thereof, the passage 70 is open so as tointroduce all of the air passing through the evaporator 44 and theheater core 52 into the front air passage 48. The rear air passage 50 isprovided with a flow rate adjusting door 74, which has a plurality ofholes, at a location downstream of the separating door 72. The flow rateadjusting door 74 is hinged on the wall of the rear air duct 50 to beoperated between positions P17 and P18. When the flow rate adjustingdoor 74 is at the position P17, the rear air passage 50 is closed bymeans of the adjusting door 74, so that the amount of the air passingthrough the rear air passage 50 is decreased behind the adjusting door74. The separating door 72 and the flow rate adjusting door 74 aredriven by an actuator motor M4.

The rear air passage 50 defines a rear vent nozzle 76 and a pair of rearfoot nozzles 78 which will be described hereafter. The rear vent andfoot nozzles 76, 78a and 78b respectively are selectively open andclosed by means of a selecting door assembly 80. The selecting doorassembly 80 is hinged on the wall of the rear air passage 50 to beoperated between positions P20 and P22. The selecting door assembly 80is driven by an actuator motor M5 and comprises a pair of selectingdoors 80a and 80b which will be described hereafter. When the selectingdoor 50 is at the position P20, the rear vent nozzle 76 is closed so asto discharge the air passing though the rear air passage 50 from therear foot nozzles 78a and 78b. On the other hand, when it is at theposition P22, the rear foot nozzles 78a and 78b are closed so as todischarge air from the rear vent nozzle 76. When the selecting doorassembly 80 is disposed at a position P21 between the positions 20 and22, air is discharged from both the rear vent and rear foot nozzles 76,78a and 78b.

As shown in FIG. 2, links 82, 84 and 86 are fixed to the defroster door64, the front vent door 66 and the front foot door 68, respectively.These links 82, 84 and 86 engage a link plate 88. The link plate 88 isrotated by means of the actuator motor M6, so that the front defroster,front vent and front foot doors 64, 66 and 68 are moved in synchronismwith each other. As will be described hereafter, the front control unit38 shown in FIG. 1 produces a control signal which is supplied to theactuator motor M6. The actuator M6 becomes active in response to thecontrol signal, so that the front defroster, front vent and front footdoors 64, 66 and 68 are moved in synchronism with each other, therebythe air conditioner system can operate in VENT mode, BI-LEVEL mode, HEATmode or defroster mode.

As seen clearly from FIG. 3, when the air conditioner system operates inVENT mode, the front vent door 66 is positioned at the position P12 sothat air is discharged from only the front vent nozzle 60. In BI-LEVELmode, the front vent door 66 is positioned at the open position P12, andthe front foot door 68 is positioned at the open position P14, so thatthe air is discharged from both the front vent nozzle 60 and the frontfoot nozzle 62. In HEAT mode, the front foot door 68 is positioned atthe open position P14, and the front defroster door 64 is positioned atthe positions P9 or P10, so that the air is discharged from both thefront foot nozzle 62 and the front defroster nozzle 58. In defroster(DEF) mode, the front defroster door 64 is positioned at the fully openposition P10, so that the air is discharged from only the frontdefroster nozzle 58.

As shown in FIGS. 2 and 4, the separating door 72 and the flow rateadjusting door 74 are fixed to a link plate 90. The link plate 90 isrotated by means of the actuator motor M4 in response to a controlsignal produced by a rear control unit 92 which will be describedhereafter. As a result, the separating door 72 and the flow rateadjusting door 74 are moved in synchronism with each other, so that theair conditioner system can selectively operate in a fully open mode, anintermediate mode or a fully close mode.

As shown in FIG. 3, when the air conditioner system operates in the fullopen mode, the separating door 72 is positioned at the position P15 toclose the opening 72, and the flow rate adjusting door 74 is positionedat the position P18 to open an opening 94 so as to discharge air fromthe rear vent nozzle 76 and/or rear foot nozzles 78a and 78b. In theintermediate mode, the separating door 72 is positioned at the positionP15 to close the opening 72, and the flow rate adjusting door 74 ispositioned at the position P17 so as to decrease the flow rate of theair discharged from the rear nozzles 76, 78a and 78b. In the fully closemode, the separating door 72 is positioned at the position P16, so thatthe air is not discharged from the rear nozzles 76, 78a and 78b and allof the air is discharged from the front nozzle 58, 60 or 62.

As shown in FIG. 5, the rear air passage 50 branches near a centerconsole 96, so that the air introduced into the rear air passage 50 isintroduced respective conditioning air passages 98 and 100 for supplyingconditioning air to the rear vehicular occupant at his breast and feetvia the rear vent nozzle 76 and the rear foot nozzles 78a and 78b,respectively. The air conditioner system also includes a humidifier 102.The air in the vehicular cabin passes through the humidifier 102 whichdischarges steam 104 to clean the air and to adjust the humidity in thecabin.

As shown in FIG. 6, the conditioning air

passage 100 consists of bifurcated passages 100a and 100b which isopened and closed by the selecting doors 80a and 80b. The selectingdoors 80a and 80b are connected to both ends of a control rod 106. Thecenter of the control rod 106 is connected to the tip of the plunger ofa solenoid 108. The plunger of the solenoid 108 moves longitudinally soas to cause the selecting door 80a and 80b to open and close insynchronism with each other. As a result, the air conditioner system canselectively operate in a rear VENT mode, a rear BI-LEVEL mode or a rearFOOT mode. In the rear VENT mode, the selecting doors 80a and 80b arepositioned at the position P22 to restrict air from being dischargedfrom the rear foot nozzles 78a and 78b, so that air is discharged fromonly the rear vent nozzle 76. In the rear BI-LEVEL mode, the selectingdoors 80a and 80b are positioned at the position P21, so that air isdischarged from all of the nozzles 76, 78a and 78b. In the rear FOOTmode, the selecting doors 80a and 80b are positioned at the position P20to restrict air from being disc:harged from the rear vent nozzle 76, sothat the air is discharged from only the rear foot nozzles 78a and 78b.

The front control unit 38 shown in FIG. 1 includes a microcomputer andproduces a control signal on the basis of various input signals. Thefront control unit 38 is electrically connected to an insolation sensor110 for monitoring the magnitude of insolation, an ambient temperaturesensor 112 for monitoring ambient temperature, an inlet temperaturesensor 114 for monitoring inlet temperature, and a water temperaturesensor 116 for monitoring temperature of water in a cooling waterpassage between the engine 34 and the heater core 52. The insolationsensor 110 comprises a phototransistor and produces a sensor signalindicative of the insolation magnitude. The ambient temperature sensor112 comprises a thermistor and produces a sensor signal indicative ofthe ambient temperature. The inlet temperature sensor 114 comprises athermistor installed downstream of the evaporator 44 and produces asensor signal indicative of the inlet temperature. The water temperaturesensor 116 produces a sensor signal indicative of temperature of waterin the cooling water passage. These sensor signals are inputted to thefront control unit 38. The front control unit 38 is also connected to aset cabin temperature indicator 118 including a manual operation switchassembly for manually setting a desired cabin temperature, and a cabintemperature sensor 120 for monitoring temperature in the vehicularcabin, which are installed on a control panel 122. The set cabintemperature indicator 118 selectively sets the desired cabin temperatureand generates a signal indicative of the set cabin temperature. Thecabin temperature sensor 120 produces a sensor signal indicative of thetemperature as monitored. The signals produced by the set cabintemperature indicator 118 and cabin temperature sensor 120 are inputtedto the front control unit 38.

The front control unit 38 outputs control signals to the compressor 28for driving a magnet relay, and to the blower 24 and the actuator motorsMl, M2 and M6.

The rear control unit 92 also receives various input signals from a rearcontrol panel 124 which will be described hereafter and the frontcontrol panel 122. The rear control unit 92 also receives the sensorsignal indicative of the inlet temperature produced by the inlet sensor114. On the basis of these signals, the rear control unit 92 outputs acontrol signal to the actuator motors M3, M4 and M5.

FIG. 7 is a block diagram of the front control unit 38. The frontcontrol unit 38 includes a microcomputer 126. The microcomputer 126 iselectrically connected to a power supply circuit 128 applying constantvoltage thereto, and a blower control circuit 130 for adjusting blowerspeed. The blower control circuit 130 includes an integrating circuitand so forth. The blower control circuit 130 outputs a control signal tothe blower 24 and receives a feedback signal from the blower 24. Themicrocomputer 126 is also connected to an output circuit 132 whichoutputs a control signal to a relay for controlling the magnetic clutchof the compressor 28. Moreover, the microcomputer 126 outputs a controlsignal to a drive circuit 134. The drive circuit 134 is electricallyconnected to the actuator motor M6 to drive the latter. The actuatormotor M6 is electrically connected to an encoder 136 which outputs afeedback signal to the microcomputer 126 via an input circuit 138. Themicrocomputer 126 also outputs a control signal to the motor Ml fordriving the intake door 22 via an output circuit 140. The sensor signalsare inputted into the microcomputer 126 via an input circuit 142 and anA/D converter 144 which converts an analog signal into a digital signal.That is, sensor signals produced by the cabin temperature sensor 120,the ambient temperature sensor 112, the inlet temperature sensor 114,the water temperature sensor 116 and the insolation sensor 110 areinputted into the input circuit 142. In addition, a sensor signalindicative of opening angle of the front air-mix door which is producedby an opening angle sensor 146 is also inputted into the input circuit142. In addition, the microcomputer 126 receives a control signalproduced by a rear manual operation switch assembly 148 which will bedescribed hereafter, and a kickdown switch signal produced upon rapidacceleration of the vehicle, via an input circuit 150.

FIG. 8 shows the front control panel 122 in detail. The front controlpanel 122 has the rear manual operation switch assembly 148 foradjusting the conditioning air discharged to the back seat, and a frontmanual operation switch assembly 152 for adjusting the conditioning airdischarged to the front seat. The rear manual operation switch assemblyincludes manual switches 154, 156 and 158 for preferentially heating theback seat, for ventilating the back seat, and for driving an air washerand the humidifier for the back seat. The front manual operation switchassembly 152 comprises a blower switch 160, a nozzle selecting switch162, a defroster switch 164, temperature setting switches 166a and 166b,intake door switches 168a and 168b, an OFF switch 170, an automaticheater switch 172 and an automatic air conditioner switch 174. The speedof the blower 24 is changed in accordance with the number of operationsof the blower switch 160. By operating the nozzle selecting switch 162,the air conditioner system can operate in VENT, BI-LEVEL and HEAT modesin turn. In response to turning on of the defroster switch 164, the airconditioner system operates in the defroster mode. When the temperaturesetting switch 166a is turned on, the set cabin temperature decreases.On the other hand, when the temperature setting switch 166b is turnedon, the set cabin temperature increases. The set cabin temperature isexhibited on the set cabin temperature indicator 118. In response toturning on of the intake door switch 168a, the air conditioner systemoperates in the fresh air mode, so that outside air is introduced intothe vehicular cabin. On the other hand, in response to turning on of theintake door switch 168b, the system operates in the recirculation mode,so that the air within the vehicular cabin is recirculated. When the OFFswitch 170 is operated, the compressor 28 and the blower 24 are turnedoff. When the automatic heater switch 172 is operated, only the blower24 is turned on. When the automatic air conditioner swich 174 is turnedon, all of the actuators, such as the compressore 28, the blower 24 andso forth, are automatically driven. An opening 176 for introducing airinto the vehiclular cabin is formed in the front control panel 122.

FIG. 9 is a block diagram of the rear control unit 92 and unitsconnected thereto. As shown in FIg. 9, the rear control unit 92 iselectrically connected to the front control unit 38. The encoder 136outputs 3-bit signals to the front and rear control units 38 and 92 inaccordance with the operation of mode of the front nozzles. The rearcontrol unit 92 is electrically connected to a separate actuator 178comprising a position switch 180 and the actuator motor M4. The rearcontrol unit 92 outputs a fully open signal, an intermediate signal or afully closed signal, by which the air conditioner system operates in thefully open mode, the intermediate mode or the fully closed mode, to theposition switch 180. The position switch 180 returns a feedback signalto the rear control unit 92. Then, the rear control unit 92 outputs acontrol signal to the actuator motor M4. The rear control unit 92 isalso connected to a selecting door actuator unit 182 including theactuator motor M5 to output a control signal to the actuator unit 182,so that the selecting door assembly 80 is selectively positioned at theposition P20, P21 or P22. In addition, the rear control unit 92 iselectrically connected to a rear air-mix door actuator unit 184including the actuator motor M3 to output a control signal to theactuator unit 184, so that the rear air-mix door 56 is selectivelypositioned at the position P6 or P7. The rear control unit 92 receives asignal serving as a RRPBR signal indicative of the actual opening angleof the rear air-mix door 56. The rear control unit 92 is furtherconnected to an air washer 186 including an actuator motor M via relays188 and 190. In response to turning ON of the relay 188, low voltage isapplied to the air washer 186. On the other hand, in response to turningON of the relay 190, high voltage is applied thereto. Moreover, the rearcontrol unit 92 receives a signal indicative of the actual opening angleof the front air-mix door 54, and the sensor signal produced by theinlet temperature sensor 114. The rear control unit 92 is also connectedto the front control panel 122 on which the manual switches 154, 156 and158 and the set cabin temperature indicator 118 comprising a pluralityof LED's are installed.

As shown in FIG. 10, the rear control panel 124 has a manual switch 192for the fine adjustment of the set temperature in the back seat, amanual switch 194 for ventilating the back seat, and a manual switch 196for driving the air washer for the back seat. The rear control panel 124is also provided with an indicator 198 which comprises a plurality ofLED's and which represents operation mode of the air washer 186,ventilation mode in the back seat and so forth. As shown in FIG. 9, themanual switches 192, 194 and 196 and the LED's of the indicator 198 areelectrically connected to the rear control unit 92.

The operation of the air conditioner system according to the inventionis described below.

FIG. 11 shows control process of the front control unit 38 according tothe present invention. At step 900, the set cabin temperature T_(PTC) isinitialized. In usual automatic air conditioner mode, the set cabintemperature T_(PTC) is initialized at 25° C. At step 1000, the sensorsignals produced by the respective sensors are inputted to the frontcontrol unit 38. That is, the sensor signals indicative of the set cabintemperature T_(PTC), the cabin temperature T_(INC), the ambienttemperature T_(AMB), the inlet temperature TINT, the water temperatureT_(W) and the magnitude of insolation Q_(SUN), respectively arerespectively inputted by the manual switches 166a and 166b installed onthe front control panel 122, the cabin temperature sensor 120, theambient temperature sensor 112, the inlet temperature sensor 114, thewater temperature sensor 116 and the insolation sensor 110. These sensorsignals serve as set cabin temperature data, cabin temperature data,ambient temperature data, inlet temperature data, water temperature dataand insolation data, respectively.

At step 1100, the ambient temperature data from the ambient temperaturesensor 112 is processed to correspond with actual ambient temperature inconsideration of the influence of other heat sources. Next, at step1200, the insolation data from the insolation sensor 110 is processed.At step 1300, the set cabin temperature data is corrected in accordancewith the ambient temperature. At step 1400, the opening angle of thefront air-mix door 54 is calculated. At step 1500, actuation of thecompressor 28 is controlled. At step 1600, the front nozzles iscontrolled. At step 1700, the open and close condition of the fresh airinlet 18 and the recirculation air inlet 20 are controlled. At step1800, the blower 24 is controlled to adjust the air flow rate.

FIG. 12 shows a control program of the processing of the ambienttemperature data, according to the invention. In execution of thecontrol program, whether or not initial data has been inputted ismonitored at step 1111 when the ignition switch IGN is turned on. Whenthe initial data is inputted, the routine goes to step 1112. At step1112, whether or not the water temperature T_(W) is less than 50° C. isestimated. The engine is not warmed immediately after being started ifit is cold, the routine then goes to step 1113. At step 1113, theambient temperature signal T_(AMB) produced by the ambient temperaturesensor 112 is set as a temperature parameter T_(A). Next, whether or notthe ambient temperature T_(AMB) is less than -20° C. is estimated atstep 1114. If the ambient temperature T_(AMB) is higher than -20° C.,the routine then goes to step 1124. At step 1124, whether or not the settemperature parameter T_(A) is less than the ambient temperature T_(AMB)is estimated. If the ambient temperature increases, i.e. when the settemperature parameter T_(A) is less than the ambient temperatureT_(AMB), the routine goes to step 1126. Immediately after the engine isstarted, the temperature in the engine compartment in which the ambienttemperature sensor 112 is installed increases rapidly due to heatradiated by the engine regardless of the actual ambient temperature.Therefore, increase of the temperature parameter T_(W) is delayed atstep 1126 so that the temperature parameter T_(W) does not increase inaccordance with temporary and rapid increase of the temperature in theengine compartment. For example, at step 1126, the temperature parameterT_(A) may be increased by 0.2° C. per 1 minute from the initial ambienttemperature T_(AMB). Then, at step 1115, the temperature parameter whichwas increased gradually at step 1126 is stored as the ambienttemperature data T_(AM) for use in various operations.

In cases where the engine is re-started after has been stoppedtemporarily for fueling at a gasoline stand or the like, the routinegoes from step 1111 to step 1112. When the engine is re-started, undersuch conditions the water temperature T_(W) of the engine is often morethan 50° C. In which case, the routine goes from step 1112 to step 1123.At step 1123, the ambient temperature data T_(AM) stored at step 1115 isset as the temperature parameter T_(A). Thereafter, the routine goes tostep 1114, and the same process is performed. After the engine isstopped, the temperature in the engine compartment is much higher thanthe actual ambient temperature due to the heat of the engine, so theambient temperature sensor 112 can not accurately monitor the actualambient temperature. Therefore, when the water temperature T_(W) ishigher than a maximum value, the temperature in the engine compartmentis disregarded, the stored value is used as the temperature parameter soas to prevent the air conditioner system from being improperlycontrolled.

In cases where the signal line or connector is temporarily brokenbetween the ambient temperature sensor 112 and the front control unit 38due to imperfect contact of the signal line or connector, at theimpedance input of the computer 126 becomes high. As a result, thecomputer 126 perceives that the ambient temperature T_(AMB) is -30° C.which is the minimum value. Since the ambient temperature T_(AMB) isperceived as being less than -20° C., the routine goes from step 1114 tostep 1115, so that the delay operation at step 1126 is cancelled.Therefore, it is possible to prevent the computer 126 from perceivingthe ambient temperature to be very low for an extended time.

FIG. 13 shows a control program of the processing of the insolationmagnitude value, according to the invention.

The insolation sensor 110 comprises a phototransistor. Current passingthrough the phototransistor is directly proportional to the magnitude ofinsolation. Therefore, current passing through the phototransistor isintegrated for a predetermined time t_(x) to be Q_(SUN) ' which is setas the insolation data.

FIG. 14 shows a control program of correction of the set cabintemperature. At step 1311, the correction value A for the set cabintemperature is set. The correction value A is zero when the ambienttemperature data T_(AM) is 20° C. When the ambient temperature dataT_(AM) is higher than 20° C., for example, 30° C., the correction valueA is -1.5° C. On the other hand, when it is lower than 20° C., forexample, -20° C., the correction value A is +4° C. At step 1321, the setcabin temperature T_(PTC) is corrected by adding the correction value A.The corrected set cabin temperature T_(PTC) ' is used in actualoperation.

FIG. 15 shows a control program of the calculation of opening angle ofthe air-mix door in FIG. 11, according to the invention. At step 1410,constants A, B, C, D and E are initialized. At step 1420, opening angleX of the air-mix door determined on the basis of the actual openingangle signal produced by the front air-mix door opening angle sensor 146is inputted. Whether or not the rear vent switch 156 or 194 is turned onis judged at step 1430. When the rear vent switch 156 and 194 are OFF,constants F and G corresponding to the inputted opening angle X of theair mix door are selected from Table (a) at step 1440. The selectedconstants F and G are used in calculation of the present heating value.

                  TABLE                                                           ______________________________________                                        (a)                (b)                                                        REAR VENT SW ON    REAR VENT SW OFF                                           X          F      G        X       F      G                                   ______________________________________                                        0 - X.sub.1                                                                              F.sub.1                                                                              G.sub.1  0 - X.sub.1                                                                           F.sub.6                                                                              G.sub.6                             X.sub.1 - X.sub.2                                                                        F.sub.2                                                                              G.sub.2  X.sub.1 - X.sub.2                                                                     F.sub.7                                                                              G.sub.7                             X.sub.2 -  F.sub.3                                                                              G.sub.3  X.sub.2 -                                                                             F.sub.8                                                                              G.sub.8                             ______________________________________                                    

On the other hand, when the rear vent switch 156 or 194 is ON, constantsF and G corresponding to the inputted opening angle X of the air mixdoor are selected from Table (b) at step 1442. Then, deviation S betweena desired discharge air temperature and the actual discharge airtemperature is calculated at step 1450. The constants F and G selectedat step 1440 or 1442 are used in the calculating of the deviation S. Thedeviation S calculated at step 1450 is estimated at step 1460. When thedeviation S is less than a predetermined value -S₀, the routine goes tostep 1470 in which the front air-mix door 54 is positioned at the coldposition, i.e. at the position P4. On the other hand, when the deviationS is greater than the value S0, the routine goes to step 1474 in whichthe front air-mix door is positioned at the hot position, i.e. theposition P5. When the deviation S is from -S₀ to +S₀, the routine goesto step 1472 in which the front air-mix door is not moved. The constantsF₁ , F₂ and F₃ in Table (a) are set to be less than the correspondingconstants F₆, F₇ and F₈ in Table (b). The constants G₁, G₂ and G₃ inTable (a) are also set to be less than the corresponding constants G₆,G₇ and G₈ in Table (b).

FIG. 16 is a flow chart of a program for controlling the compressor 28at step 1500 in FIG. 11. At step 15, whether or not the blower 24 is ONis estimated. When the blower 24 is OFF, the routine goes to step 1570in which the compressor 28 is turned off. On the other hand, when, atstep 1510, it is estimated that the blower 24 is ON, the routine goes tostep 1520 in which whether or not the defroster switch 164 is 0N isdetermined. When the defroster switch 164 is ON, the routine goes fromstep 1520 to step 1540. On the other hand, when the defroster switch 164is OFF, the routine goes to step 1530 in which whether or not the airconditioner switch 174 is ON is determined. When the air conditionerswitch 174 is OFF, the routine goes to step 1570 in which the compressor28 is turned off. 0n the other hand, when the air conditioner switch 174is ON, the routine goes from step 1530 to step 1540. At step 1540, it isdetermined whether or not the process for protecting the compressor 28at very low ambient temperature is required. That is, while the ambienttemperature data T_(AM) is decreasing, the routine goes from step 1540to step 1550 until the ambient temperature data T_(AM) reaches apredetermined value T_(AM3). When the ambient temperature data T_(AM)becomes less than the value T_(AM3), the routine goes from step 1540 tostep 1570 in which the compressor 28 is turned off. On the other hand,while the ambient temperature data T_(AM) is increasing, the routinegoes from step 1540 to step 1570 until the ambient temperature dataT_(AM) reaches a predetermied value T_(AM2). When the ambienttemperature data T_(AM) becomes greater than the value T_(AM2), theroutine goes from step 1540 to 1550. At step 1550, whether or not thekickdown switch is turned on is determined. If the kickdown switch isturned on, the routine goes to step 1570 in which the compressor 28 isturned off. On the other hand, if the kickdown switch is not turned on,the routine goes from step 1550 to step 1560 in which the compressor 28is turned on.

FIG. 17 is a flow chart of the first preferred embodiment of a controlprogram for controlling the discharge nozzles at step 1600 in FIG. 11.At step 1611, whether or not the discharge nozzle selecting switch 162is ON is judged. When the discharge nozzle selecting switch 162 is ON,the routine goes from step 1611 to step 1613 in which whether or not theair conditioner system is operating in VENT mode is determined. When thesystem is operating in VENT mode, the routine goes to step 1615 in whicha signal is outputted to the actuator motor M6 so as to open the frontvent door 66. On the other hand, when the system is not operating inVENT mode, the routine goes from step 1613 to step 1617 in which whetheror not the system is operating in BI-LEVEL mode is determined. When thesystem is operating in BI-LEVEL mode, the routine goes from step 1617 tostep 1625 in which it is determined whether or not the compressor 28 isON. When the compressor 28 is ON, the routine goes from step 1625 tostep 1627 in which the operation mode of the system is set to beBI-LEVEL mode 1. In BI-LEVEL mode 1, the front vent door 66 and thefront foot door 68 are open. At step 1625, when it is determined thatthe compressor 28 is OFF, the routine goes from step 1625 to step 1629in which the operation mode thereof is set to be BI-LEVEL mode 2. In theBI-LEVEL mode 2, the front vent door 66, the front foot door 68 and thefront defroster door 64 are open.

When the operation mode of the system is neither VENT mode nor BI-LEVELmode, the routine goes from step 1617 to step 1619 in which whether ornot the operation mode is HEAT mode is determined. When the systemoperates in HEAT mode, the routine goes from step 1619 to step 1623 inwhich the operation mode is set to be DEF-FOOT mode 1. At the DEF-FOOTmode 1, the front defroster door 64 is positioned at the position P9,and the front foot door 68 is positioned at the position P14. Therefore,at the DEF-FOOT mode 1, the proportion of the air flow discharged fromthe front defroster door 64 to that from the front foot door 68 is set,for example, 1 to 9.

When the operation mode is neither VENT mode, BI-LEVEL mode nor HEATmode, the routine goes from step 1619 to step 1621 in which theoperation mode is set to be DEF mode. At DEF mode, the front defrosterdoor 64 is positioned at fully open the position 10.

At step 1611, when it is determined that the discharge nozzle selectingswitch 162 is OFF, i.e. that the air conditioner system is operating inautomatic air conditioner mode, the routine goes from step 1611 to step1631 in which the insolation data Q_(SUN) is read. Then, at step 1633,weighted mean is calculated on the basis of the insolation data Q_(SUN)in order to select the discharge nozzle mode. At step 1633, until theinsolation data Q_(SUN) decreases to Q_(B) calories, the weighted meanSU is set to be 2. If the insolation data Q_(SUN) further decreases, theweighted mean SU is set to be 1 until the insolation data Q_(SUN)reaches zero calories. On the other hand, when the isolation dataQ_(SUN) increases, the weighted means SU is set to be zero while theinsolation data Q_(SUN) is between zero and Q_(C) calories. Thereafter,while the insolation data Q_(SUN) further increases to Q_(A) calorie,the weighted means SU is set to be 1. When the insolation data Q_(SUN)further increases to be greater than Q_(A) calorie, the weighted mean isset to be 2. Thereafter, the routine goes to step 1635 in which theweighted mean set at the last step 1633 is estimated. When the weightedmean SU is zero, the routine goes to step 1643 via step 1637. When theweighted mean SU is 1, the routine goes to step 1643 via step 1639. Whenthe weighted mean SU is 2, the routine goes to step 1642 via step 1641.At these steps 1637, 1639 and 1641, constants H, I, J and K are set.Only the constants J and K are changed in accordance with the value ofthe weighted mean SU. The constant J₁ is greater than J₀, and theconstant J₂ is greater than J₁. The constant K₁ is greater than K₀, andthe constant K₂ is greater than K₁. At step 1643, a required dischargeair temperature X_(M) is calculated. Then, the routine goes to step 1645in which the discharge nozzle mode is set on the basis of the requireddischarge air temperature X_(M) calculated at step 1643. At step 1645,until the required discharge air temperature X_(M) decreases to thevalue J, the operation mode is set to be HEAT mode. Thereafter, whilethe required discharge air temperature X_(M) further decreases to thevalue H, the operation mode is set to be BI-LEVEL mode. On the otherhand, until the required discharge air temperature X_(M) increases tothe value I, the operation mode is set to be VENT mode. Thereafter,while the required discharge air temperature X_(M) further increases tothe value K, the operation mode is set to be BI-LEVEL mode. If therequired discharge air temperature X_(M) further increases to be greaterthan the value K, the operation mode is set to be HEAT mode. Therefore,by changing the values J and K in accordance with the weighted mean SU,the mode switching point between the HEAT mode and the BI-LEVEL mode canbe changed in accordance with the magnitude of insolation. Thereafter,the routine goes from step 1645 to step 1647 in which whether or not theset discharge nozzle mode is VENT mode is determined. When set dischargenozzle mode is VENT mode, the routine goes to step 1649 in which thefront vent door 66 is opened so that the air is discharged from thefront vent nozzle 60. When the operation mode is not VENT mode, theroutine goes from step 1647 to step 1651 in which whether or not theoperation mode is BI-LEVEL mode is determined. When it is BI-LEVEL mode,the routine goes to step 1653 in which whether or not the compressor 28is ON is determined. When the compressor 28 is ON, the routine goes fromstep 1653 to step 1655 in which the operation mode is set to beBI-LEVEL 1. In the BI-LEVEL mode 1, the front vent door 66 and the frontfoot door 68 are open. On the other hand, when the compressor 28 is OFF,the routine goes from step 1653 to step 1657 in which the operation modeis set to be BI-LEVEL mode 2. In the BI-LEVEL mode 2, the front ventdoor 66, the front foot door 68 and the front defroster door 64 areopen.

When the operation mode is neither VENT mode nor BI-LEVEL mode, theroutine goes from step 1651 to step 1659 in which a specific HEAT mode,for example DEF-FOOT mode 1 or DEF-FOOT mode 2, is set among a pluralityof HEAT modes in accordance with the ambient temperature data T_(AM).While the ambient temperature data T_(AM) decreases towards the valueT₁, for example, -3° C., the operation mode is set to be DEF-FOOTmode 1. On the other hand, while the ambient temperature data T_(AM)increases toward the value T₀, for example, 0° C., the operation mode isset to be DEF-FOOT mode 2. When the ambient temperature data T_(AM)further increases to be greater than the value T₀, the operation mode isset to be DEF-FOOT mode 1. At the DEF-FOOT mode 1, the front defrosterdoor 64 is positioned at the position P9, and the front foot door 68 ispositioned at the position P14. On the other hand, at the DEF-FOOT mode2, the front defroster door 64 is positioned at the position P10, andthe front foot door 68 is positioned at the position p14. Therefore, theflow rate of the air discharged from the front defroster nozzle 58 atthe DEF-FOOT mode 1 is less than that at the DEF-FOOT mode 2.

FIG. 18 shows a flow chart of a program for controlling the inlets atstep 1700 in FIG. 11. At step 1711, whether or not the ignition switchis ON is judged. When the ignition switch is turned on, the routine goesto step 1771 in which the intake door 22 is positioned at the positionP3 in FIG. 1 so that the operation mode is set to be the fresh air mode.Next routine goes from step 1711 to step 1721 in which whether or notthe defroster switch 164 is ON is judged. If the defroster switch 164 isON, the routine goes from step 1721 to step 1771 in which the operationmode is set to be the fresh air mode. On the other hand, if thedefroster switch 164 is not ON, the routine goes from step 1721 to step1731 in which whether or not the recirculation switch, i.e. the intakedoor switch 168a is ON is judged. If the intake door switch 168a is ON,the routine goes to step 1741 in which the intake door 22 is positionedat the position P1 so that air is drawn into the recirculation airnozzle 20, i.e. the operation mode is set to be the recirculation mode.On the other hand, when the intake door switch 168a is OFF, the routinegoes from step 1731 to step 1751 in which whether or not the fresh airmode switch, i.e. the intake door switch 168b is ON is judged. If theintake door switch 168b is ON, the routine goes to step 1771 in whichthe operation mode is set to be the fresh air mode. On the other hand,when the intake door switch 168b is OFF, the routine goes from step 1751to step 1761 in which whether or not the compressor 28 is ON isdetermined. When the compressor 28 is OFF, the routine goes to step 1771in which the operation mode is set to be the fresh air mode. On theother hand, when the compressor 28 is ON, the routine goes from step1761 to step 1781 in which the inlet mode is controlled in accordancewith the required discharge air temperature X_(M). At step 1781, untilthe required discharge air temperature X_(M) decreases gradually to beT₁₂ ° C., the inlet mode is set to be the fresh air mode. When therequired discharge air temperature X_(M) further decreases between T₁₂ °C. and T₁₀ ° C., the inlet mode is set to be F/R mode in which bothfresh air and recirculation air are introduced into the conditioning airduct assembly 10. That is, in the F/R mode, the intake door 22 ispositioned at the position P2, so that the air in the vehicular cabin isintroduced into the duct assembly 10 from the recirculation air inlet20, and the fresh air is introduced into the duct assembly 10 from thefresh air inlet 18. When the required discharge air temperature X_(M) isless than T₁₀° C., the inlet mode is set to be the recirculation mode.On the other hand, when the required discharge air temperature X_(M)increases, the inlets remains in the recirculation mode until thetemperature X_(M) reaches T₁₁ ° C. When the required discharge airtemperature X_(M) further increases, the inlet mode is set to be F/Rmode until the temperature reaches T₁₃ ° C. When the required dischargeair temperature X_(M) further increases to be greater than T₁₃ ° C., theinlet mode is set to be the fresh air mode. Furthermore, the temperatureT₁₁ is greater than T₁₀, the temperature T₁₂ is greater than T₁₁, andthe temperature T₁₃ is greater than T₁₂.

In FIGS. 17 and 18, although the setting of the inlets and the selectingof the discharge nozzles is controlled on the basis of the requireddischarge air temperature X_(M), it can be controlled on the basis ofthe actual discharge air temperature. That is, the following formula isused at step 1643 in FIG. 17, and the setting of the discharge airnozzles and the inlets can be performed on the basis of X_(M) ' at step1645 in FIG. 17 and at step 1781 in FIG. 18, respectively.

    X.sub.M '=(FX+G)(82-T.sub.INT)+T.sub.INT

FIG. 19 is a flow chart of a program for controlling the air flow rateat step 1800 in FIG. 11. At step 1801, whether or not the OFF switch 170is operated is determined. If the OFF switch 170 has been operated, theroutine goes to step 1803 in which the blower 24 is turned off. On theother hand, if the OFF switch 170 has not been operated, the routinegoes from step 1801 to step 1805 in which whether or not the blowerswitch 160 is ON is determined. When the blower switch 160 is ON, theroutine goes from step 1805 to step 1807 in which whether or not theblower 24 is to operate at a low speed is determined. If the blower 24is to operate at the lowest speed, i.e. a first speed, the routine goesfrom step 1807 to step 1811 in which 5-volt current is applied to theblower 24. At step 1807, if it is estimated that the blower 24 shouldnot operate at the lowest speed, the routine goes to step 1809 in whichwhether or not the blower 24 should operate at a medium speed, i.e. at asecond speed is determined. When the blower 24 is to operate at thesecond speed, the routine goes from step 1809 to step 1813 in which8-volt current is applied to the blower 24. When the blower 24 is tooperate at neither the first speed nor the second speed, the routinegoes from step 1809 to step 1815 in which 12-volt current is applied tothe blower 24 so that the blower 24 operates at a high speed.

At step 1805, when it is estimated that the blower switch 160 is OFF,the routine goes to step 1817 in which whether or not the defrosterswitch 164 is 0N is determined. When the defroster switch 164 is OFF,the routine goes from step 1817 to step 1819 in which it is determinedwhether or not the discharge nozzle is in the VENT mode. When thedischarge nozzle mode is not the VENT mode, the routine goes from step1819 to step 1821 in which whether or not the water temperature T_(W) ofthe engine 34 is less than the value T_(W0), for example, 35° C., andwhether or not the ambient air temperature data T_(AM) is less than thevalue T_(AM0), for example, 15° C. are determined. When the watertemperature T_(W) of the engine 34 is less than the value T_(WO), andthe ambient air temperature data T_(AM) is less than the value T_(AM0),the routine goes from step 1821 to step 1823 in which whether or not thewater temperature T_(W) of the engine 34 is less than the value T_(W1),for example, 32° C. which is less than the value T_(WO) is determinedagain. When the water temperature T_(W) of the engine 34 is less thanthe value T_(W1), the routine goes from step 1823 to step 1825 in whichthe blower 24 is turned off for a predetermined time t₁. On the otherhand, at step 1823, when it is estimated that the water temperatureT_(W) is not less than the value T_(W1), the routine goes from step 1823to step 1827. At step 1827, electrical current is applied to the blower24 in such a manner that the lowest voltage, i.e. 5-volts is applied tothe blower 24 and thereafter increased gradually to the maximum voltage,i.e. 10.5-volts after a predetermined time t₂. At step 1821, when it isestimated that either the water temperature T_(W) is greater than thevalue T_(W0) or the ambient air temperature data T_(AM) is greater thanthe value T_(AM0), the routine goes from step 1821 to step 1829. At step1829, whether or not the blower switch 160 is ON is determined. When theblower switch is ON, the routine goes from step 1829 to step 1831 whichrestricts voltage from being suddenly applied to the blower 24 in orderto prevent the brush of the blower 23 from wearing out. That is, at step1831, first 5-volt current is applied to the blower 24 and thereafterthe voltage is increased gently to 10-volts during a predetermined timet₃.

When the automatic air conditioner mode is selected, and the defrosterswitch 164 is ON, the routine goes from step 1817 to step 1833. Inaddition, at step 1829, when it is estimated that the blower switch 160is ON, the routine goes from step 1829 to step 1833. At step 1833, theconstants L, M, N and P are initialized to be L₀, M₀, N₀ and P₀.Thereafter, the routine goes from step 1833 to step 1835 in whichwhether or not the operation mode is VENT mode is determined. When theoperation mode is not VENT mode, the routine goes to step 1839. On theother hand, when the operation mode is VENT mode, the routine goes tostep 1839 via step 1837 in which the correction voltage B of theimpressed reference voltage V_(F) which is applied to the blower 24 isset in accordance with the magnitude of insolation Q_(SUN). At step1837, until the magnitude of insolation Q_(SUN) decreases to Q_(E)calories, the correction voltage B is set at 1.0 volt. Thereafter, untilthe magnitude of insolation Q_(SUN) further decreases to Q_(G) calories,the correction voltage B is set to be 0.5 volt. When the magnitude ofinsolation Q_(SUN) becomes less than Q_(G) calorie, the correctionvoltage B is set at zero. On the other hand, until the magnitude ofinsolation Q_(SUN) increases to Q_(F) calories, the correction voltage Bis set at zero. Until the magnitude of insolation Q_(SUN) furtherincreases to Q_(D) calorie, the correction voltage B is set at 0.5 volt.When the magnitude of insolation Q_(SUN) becomes greater than Q_(D)calories, the correction voltage B is set at 1.0 volt. At step 1839, theimpressed reference voltage V_(F) which is applied to the blower 24 isdetermined in accordance with the required discharge air temperatureX_(M). Since rapid cooling or heating must be performed when therequired discharge air temperature X_(M) is greater or less than apredetermined value, the impressed reference voltage V_(F) applied tothe blower 24 is set to be relatively high. On the other hand, when therequired discharge air temperature X_(M) is usual value, for example,between M and N, the impressed reference voltage V_(F) applied to theblower 24 is set to be the minimum voltage. That is, when the dischargenozzle is in the VENT mode, the impressed reference voltage V_(F) is setat 5-volts+the correction voltage B. On the other hand, when thedischarge nozzle mode is not VENT mode, the minimum impressed referencevoltage V_(F) which is applied to the blower 24 is set at 6-volts.Thereafter, the routine goes to step 1841 in which a correctioncoefficient A is set in accordance with the ambient temperature dataT_(AM). That is, When the ambient temperature data T_(AM) is greaterthan a predetermined value T_(AM) 10 or less than T_(AM) 30 thecorrection coefficient A is set at 1. When the ambient temperature dataT_(AM) is between T_(AM) 30 and a predetermined value T_(AM) 20, thecorrection coefficient A is determined in accordance with a givencharacteristic curve in step 1841. When the ambient temperature dataT_(AM) is between T_(AM) 20 and T_(AM) 10, the correction coefficient Ais set at 0.5. The routine then goes to step 1843 in which it isdetermined whether or not either of the rear vent switches 156 or 194 isON. If either of the rear vent switches 156 or 194 is ON, the routinegoes to step 1847. On the other hand, if both of the rear vent switches156 and 194 are OFF, the routine goes to step 1845. At steps 1845 and1847, the impressed voltage V_(F) ' applied to the blower 24 isdetermined by a predetermined operational expression in accordance withwhether or not the front nozzle is in the VENT mode. When the impressedvoltage V_(F) ' applied to the blower 24 is calculated, the correctioncoefficient A determined at step 1841 is used. If the ambient conditionsare the same, the impressed voltage V_(F) ' applied to the blower 24when either the rear vent switch 156 or 232 is ON is greater than thatwhen both of the switches 156 and 232 are OFF.

When the operation described in the flow chart in FIG. 19 is executed,the routine returns to step 1000 in FIG. 11.

FIG. 20 shows a fundamental control process of the rear control unit 92according to the present invention. At step 2000, the separating door 72and the flow rate adjusting door 74 is controlled. Next, at step 2100,the rear air-mix door 56 is controlled. Then, at step 2000, openingangle of the selecting door assembly 80 is controlled.

FIG. 21 shows a control program of the separating door 72 according tothe present invention. At steps 2011, 2013 and 2015, the front dischargenozzle mode is judged in accordance with 3-bit feedback signal suppliedby the encoder 136. At step 2011, when it is estimated that the frontdischarge nozzle mode is DEF mode, the routine goes to step 2021 inwhich the fully open operation mode is set. In the full close mode, theseparating door 72 is positioned at the position P16 so that the opneing70 is open and the rear air passage 50 is closed. Therefore all of theair is discharged from the front discharge nozzles. On the other hand,when the front discharge nozzle mode is not DEF mode, the routine goesfrom step 2011 to wtep 2013 in which it is determined whether or not thefront discharge nozzle mode is VENT. If it is VENT mode, the routinegoes to step 2031 in which it is determined whether or not either therear vent switch 156 or 194 is ON. When both of the rear vent switch1566 or 194 are OFF, the routine goes to step 2021 so that the operationmode is set as the fully closed mode. On the other hand, when the eitherthe rear vent switch 156 or 194 is ON, the routine goes from step 2031to step 2051 in which the operation mode is set as the fully open mode.In the fully open mode, the separating door 72 is set at the positionP15 and the flow rate adjusting door 74 is set at the position P18. Atstep 2013, when it is judged that the front discharge nozzle mode is notVENT, the routine goes from step 2013 to step 2015 in which whether ornot the front discharge nozzle mode is BI-LEVEL is judged. When thefront discharge nozzle mode is BI-LEVEL mode, the routine goes to step2061, so that the operation mode is set as the intermediate mode. In theintermediate mode, the separating door 72 is positioned at the positionP15 and the flow rate adjusting door 74 is positioned at the positionp17. As a result, the amount of air passing through the rear air passage50 is decreased by the flow rate adjusting door 74, so that the airdischarged from the rear discharge nozzles is decreased compared to thatin the fully open mode, and the air discharged from the front dischargenozzles increases. At step 2015, when it is judged that the frontdischarge nozzle mode is not BI-LEVEL, i.e. when the front dischargenozzle mode is HEAT, the routine goes from step 2015 to step 2041 inwhich whether or not the manual switch 154 for preferentially heatingthe back seat is ON is estimated. If the manual switch 154 is ON, theroutine goes to step 2051 so that the full open mode is set. On theother hand, if the manual switch 154 is OFF, the routine goes to step2061 in which the system is set in the intermediate mode.

FIG. 22 shows the control program for the rear air-mix door at step 2100in FIG. 20. At step 2101, the actual opening angle signal of the frontair-mix door 54 is read. Then, at step 2111, operation condition of theblower 24 is estimated on the basis of the impressed voltage applied tothe blower 24. That is, if the impressed voltage V_(F) ' applied to theblower 24 is increasing until it reaches a predetermined voltage V_(F)'l (V), it is determined that the operation condition of the blower 24is the stable operating condition 1, and the routine goes from step 2111to step 2121. On the other hand, if the impressed voltage V_(F) 'applied to the blower 24 is decreasing until it reaches a predeterminedvoltage V_(F) '2 (V), it is determined that the operation conditionthereof is the condition 2 in which rapid cooling is occuring, and theroutine goes from step 2111 to step 2123. At step 2121, opening angleX_(R) of the rear air-mix door 56 is calculated with reference to acorrection coefficient R relative to the opening angle X_(F), and theset temperature T_(PTCRR) set by the manual switch 192 for the fineadjustment of the set temperature in the back seat. As shown in FIG. 23,the set temperature T_(PTCRR) set by the manual switch 192 is set to bezero when the manual switch 192 is positioned at the center, and can bechanged between -1 and +1 in accordance with the position of the manualswitch 192. At step 2123, the opening angle X_(R) of the rear air-mixdoor 56 is set to be equal to the opening angle X_(F) of the frontair-mix door 54. The routine then goes from step 2121 or 2123 to step2131 in which whether or not the front discharge nozzle mode is BI-LEVELmode is estimated. When the front discharge nozzle mode is BI-LEVEL, theroutine goes from step 2131 to step 2133. When in BI-LEVEL mode, morecool air bypasses the heater core 52 and is discharged from the frontvent nozzle 60, so that the temperature of the air discharge from thefront bent nozzle 60 is less than that discharged from the front footnozzle. As a result, the vehicular occupant may get warm air at his feetand be cool air near his head. However, when the air is discharged fromthe rear discharge nozzles 76 and 78, the air passing through the heatercore 52 becomes sufficiently mixed with the air bypassing the latter dueto the long air passage between the rear discharge nozzles 76 and 78 andthe heater core 52. As a result, the air passing through the rear airpassage 50 is cooled, so that the discharged air temperature may belower than the required discharge air temperature which was calculated.Therefore, at step 2133, the front air-mix door 56 is moved in adirection of the position P₇. At step 2131, when it is estimated thatthe front discharge nozzle mode is not BI-LEVEL, the routine goes fromstep 2131 to step 2141 in which opening angle X₀ of the rear air-mixdoor 56, in which temperature of the air discharged from the reardischarge nozzles 76 and 78 is a predetermined temperature T₃₀, iscalculated on the basis of the inlet air temperature data TINT obtainedby the inset air temperature sensor 114. The temperature T₃₀ is theminimum temperature for the air discharged from the rear foot nozzles78. When air of this temperature is blown against the occupant's feet,he may feel uncomfortable. At step 2141, L, M and N are constants, and Mand N are set on the basis of the inlet air temperature T_(INT).Thereafter, the routine goes from step 2141 to step 2151 in whichwhether or not the rear discharge nozzle is in the foot mode isestimated. When the rear discharge is in the foot mode, the routine goesfrom step 2151 to step 2161 in which the opening angle X_(R) of the rearair-mix door 56 calculated at steps 2121, 2123 or 2133 is compared withthe opening angle X₀ calculated at step 2141. When the value X_(R) isless than the value X₀, i.e. when the temperature of the air dischargedfrom the rear discharge nozzles is lower than the temperature T₃₀, theroutine goes to step 2171 wherein the opening angle X_(R) of the rearair-mix door 56 is set at the opening angle X₀ calculated at step 2141.At step 2151, if it is estimated that the rear discharge nozzle mode isnot FOOT, i.e. that the air is discharged from only the rear vent nozzle76, or from both of the rear vent nozzle and rear foot nozzles 78, theroutine goes from step 2152 to step 2173. At step 2161, if it isestimated that the value X_(R) is greater than the value X₀, the routinegoes from step 2161 to step 2173. At step 2173, the opening angle X_(R)of the rear air-mix door 56 is set to be the same value as thatcalculated at steps 2121, 2123 or 2133. Thereafter, the routine goesfrom step 2171 or 2173 to step 2181 in which the opening angle signalX_(PBRRR) indicative of the actual opening angle of the rear air-mixdoor 56, which is produced from the rear air-mix door actuator 184 shownin FIG. 9, is compared with the opening angle X_(R) of the rear air-mixdoor 56 determined by the rear control unit 92. When the opening anglesignal X_(PBRRR) is less than the opening angle X_(R), the routine goesto step 2191 in which the rear air-mix door 56 is moved toward the hotposition, i.e. the position P7. When the opening angle signal X_(PBRRR)is greater than the opening angle X_(R), the routine goes to step 2193in which the rear air-mix door 56 is moved in a direction of the coldposition, i.e. the position P6. When the opening angle signal X_(PBRRR)is equal to the opening angle X_(R), the routine goes to step 2195 inwhich the rear air-mix door is not moved.

FIG. 24 shows a control program of the selecting door assembly 80 atstep 2200 in FIG. 20. At step 2211, whether or not the front dischargenozzle mode is DEF is determined. When the front discharge nozzle modeis not DEF, the routine goes to step 2221 in which whether or not eitherof the rear vent switches 156 or 194 is ON is determined. If either ofthe rear vent switches 156 or 194 is ON, the routine goes to step 2231in which whether or not the front discharge nozzle mode is VENT isdetermined. If the front discharge nozzle mode is VENT, the routine goesfrom step 2231 to step 2251 in which the rear VENT mode is set, i.e. theselecting door assembly 80 is positioned at the position P22 so that airis discharged from only the rear vent nozzle 76. At step 2231, if thefront discharge nozzle mode is not VENT, i.e. when it is BI-LEVEL orHEAT, the routine goes from step 2231 to step 2241 in which thedischarged air temperature is determined. The decision 35 made at step2241 is same as that at step 2161 in FIG. 22. When X_(R) >X₀, theroutine goes from step 2241 to step 2251 in which the the air introducedinto the rear air passage 50 is caused to be discharged from only therear vent nozzle 76. Therefore, when temperature of the air dischargedto the back seat is lower than a predetermined T_(B0), the rear footnozzles 78 are closed so as to prevent cool air from being blown againstthe feet of occupant on the back seat. On the other hand, when X_(R)≦X₀, the routien goes from step 2241 to step 2253 in which the rear ductsystem is set in the rear BI-LEVEL mode, i.e. the selecting doorassembly 80 is moved into the position P21 so that air is dischargedfrom both of the rear vent nozzle 76 and the rear foot nozzles 78.

At step 2221, when both of the rear vent switches 156 and 194 are OFF,the routine goes from step 2221 to step 2233 in which whether or not thefront discharge nozzle mode is VENT is determined. When the frontdischarge nozzle mode is not VENT, i.e. when it is BI-LEVEL or HEAT, theroutien goes to step 2255 in which the rear duct system is set in therear FOOT mode, i.e. the selecting door assembly 80 is positioned at theposition P20, so that the rear vent nozzle 76 is closed, thereby the airis discharged from only the rear foot nozzles 78. At step 2211, if thefront discharge nozzle mode is DEF, the routine goes from step 2211 tostep 2243. At step 2233, the front discharge nozzle mode is VENT, theroutine goes from step 2233 to step 2243. At step 2243, the selectingdoor assembly 80 is not moved.

FIG. 25 shows the second preferred embodiment of a control program forcontrolling the discharge nozzle at step 1600 in FIG. 11, according tothe invention. The routine from step 1611 to step 1643 is same as thatof the first preferred embodiment shown in FIG. 17. According to thesecond preferred embodiment of the invention, after the requireddischarge air temperature X_(M) is calculated at step 1643, the routinegoes to step 1645 in which the discharge nozzle mode is set on the basisof the required discharge air temperature X_(M) calculated at step 1643.At step 1645, while the required discharge air temperature X_(M)decreases until it reaches the value J, the system is operated inDEF-FOOT mode 1 of the HEAT mode. If the required discharge airtemperature X_(M) decreases further, until it reaches the value H, theoperation mode is set as BI-LEVEL. On the other hand, if the requireddischarge air temperature X_(M) increases, until it reaches the value I,the operation mode is set as VENT. If the required discharge airtemperature X_(M) increases further, until it reaches the value K, theoperation mode is set as BI-LEVEL. If the required discharge airtemperature X_(M) exceeds the value K, the system is operated in theDEF-FOOT mode of the HEAT mode. Therefore, by changing the values J andK in accordance with the weighted mean SU, the mode switching pointbetween the HEAT mode and the BI-LEVEL mode can be changed in accordancewith the magnitude of insolation. In addition, if the required dischargeair temperature X_(M) exceeds the value Z₁, the system is set in theDEF-FOOT mode 2 of the HEAT mode is set. On the other hand, if therequired discharge air temperature X_(M) decreases, until it reaches thevalue Z₁, the DEF-FOOT mode is selected. Furthermore, the value Z₁ isthe temperature of the air discharged into the vehicular cabin under astable condition, in which the actual cabin temperature is essentiallyequal to the set temperature, when the ambient temperature data T_(AM)is the value T_(AM2). The value Z₁ is experimentally determined. Thevalue Z₂ is temperature of the air discharged into the cabin under thestable condition when the ambient temperature data is the value T_(AM1)Thereafter, the routine goes from step 1661 to step 1663 in whichwhether or not the set discharge nozzle mode is VENT is determined. Whenthe set discharge nozzle mode is VENT, the routine goes to step 1665 inwhich the front vent door 66 is opened so that air is discharged fromthe front vent nozzle 60. When the operation mode is not VENT, theroutine goes from step 1663 to step 1667 in which whether or not theoperation mode is BI-LEVEL is determined. When it is BI-LEVEL mode, theroutine goes to step 1669 in which whether or not the compressor 28 isON is determined. If the compressor 28 is ON, the routine goes from step1669 to step 1671 in which the operation mode is set as BI-LEVEL 1. Inthe BI-LEVEL mode 1, the front vent door 66 and the front foot door 68are open. On the other hand, if the compressor 28 is OFF, the routinegoes from step 1669 to step 1673 in which the operation mode is set asBI-LEVEL mode 2. In the BI-LEVEL mode 2, the front vent door 66, thefront foot door 68 and the front defroster door 64 are open.

If the operation mode is neither VENT nor BI-LEVEL, the routine goesfrom step 1667 to step 1675 in which it is determined whether or not thedischarge nozzle mode set at step 1661 is the DEF-FOOT mode 1 of theHEAT mode. If the discharge nozzle mode is not the DEF-FOOT, the routinegoes to step 1679 in which the DEF-FOOT mode 2 is set so that a drivingsignal is outputted to the front defroster door 64 and the front footdoor 68. At step 1675, if it is recognized that the DEF-FOOT mode 1 hasbeen selected, the routine goes from step 1675 to step 1677 in which theDEF-FOOT mode 1 or 2 is selected in accordance with the ambient airtemperature data T_(AM) regardless of the discharge nozzle mode. Thatis, if the ambient temperature data T_(AM) is decreasing, until itreaches the value T_(AM1), for example, -10° C., the DEF-FOOT mode 1 isselected. On the other hand, if the ambient temperature data T_(AM) isincreasing, until it reaches the value T_(AM2), for example, -5° C., theDEF-FOOT mode 2 is selected. If the ambient temperature data T_(AM)increases above the value T₀, the DEF-FOOT mode 1 is selected. In theDEF-FOOT mode 1, the front defroster door 64 is disposed in the positionP9, and the front foot door 68 in the position P14. On the other hand,in the DEF-FOOT mode 2, the front defroster door 64 is disposed in theposition P10, and the front foot door 68 in the position P14. Therefore,the air flow rate discharged from the front defroster nozzle 58 at theDEF-FOOT mode 1 is less than that in the DEF-FOOT mode 2.

According to the second preferred embodiment of the invention, theDEF-FOOT mode 1 or 2 is set compulsorily at step 1677 in accordance withthe ambient air temperature. Therefore, when the required dischargenozzle temperature X_(M) is lower than the value Z₁ under the stablecondition, in which the actual cabin temperature is essentially equal tothe set temperature, at a low ambient temperature, the DEF-FOOT mode canbe set so as to effectively prevent fogging of the windows.

What is claimed is:
 1. An air conditioner system for an automotivevehicle, comprising:air passage means defining an air path and includingfirst and second air outlets which open into a vehicular cabin fordischarging conditioned air into said vehicular cabin, said first airoutlet being directed to a windshield for discharging conditioned airdirectly thereto, and said second air outlet being directed to a lowerportion of said vehicular cabin for discharging conditioned air towardsaid lower portion; air conditioning means, disposed within said airpassage means, said air conditioning means including a cooling air unitfor cooling air flowing through said air passage means and a heatingunit for heating air flowing through said air passage means, saidcooling and heating units being cooperative for generating conditionedair of a desired temperature to be discharged into said vehicular cabin;a first door, associated with said first air outlet, operable between aclosed position inwhich said first door fully closes said first airoutlet in a first operation mode of said air conditioner system and anopen position in which said first door fully opens said first air outletin a second operation mode of said air conditioner system, said firstdoor being positioned at an intermediate position between said open andclosed positions in a third operation mode of said air conditionersystem and being positioned at said open position in a fourth operationmode of said air conditioner system; a second door, associated with saidsecond air outlet, oeprable between a closed position in which saidsecond door fully closes said second air outlet in said second operationmode and an open position in which said second door fully opens saidsecond air outlet ins aid first operation mode, said second door beingpositioned at said open position in said third and fourth operationmodes; actuator means for driving said first and second doors forvarying opening angles of said first and second doors between saidclosed positions and open positions; and control means for selecting oneof said operation modes, associated with said actuator means, foradjusting the proportion of said conditioned air discharged from saidfirst air outlet and that from said second air outlet, said controlmeans selecting one of said third and fourth operation modes dependingupon ambient air temperature.